US officer 'recklessly' killed Justine

Australian life coach Justine Damond put her hands on the bullet wound on the left side of her stomach and said "I'm dying" just moments after a Minneapolis police officer shot her, according to the prosecutor who announced murder and manslaughter charges against Mohamed Noor .

Officer Noor turned himself in to Minneapolis authorities on Tuesday after a warrant was issued for his arrest.

He was booked into Hennepin County jail with bail set at $US500,000, and he is expected to make his first appearance in a Minneapolis court on Wednesday.

Ms Damond's family is pleased justice may be served.

"While we have waited more than eight months to come to this point, we are pleased with the way a grand jury, and County Attorney Mike Freeman, appear to have been diligent and thorough in investigating and ultimately determining that these charges are justified," Damond's fiance Don and her Sydney-based father John Ruszczyk and other family members said in a joint statement.

"We remain hopeful that a strong case will be presented by the prosecutor, backed by verified and detailed forensic evidence, and that this will lead to a conviction.

"No charges can bring our Justine back. However, justice demands accountability for those responsible for killing the people they are sworn to protect."

"The facts will show that Officer Noor acted as he has been trained and consistent with established departmental policy," Mr Plunkett said.

"Officer Noor should not have been charged with any crime."

Minneapolis' prosecutor, Hennepin County Attorney Mike Freeman, told a different story on Tuesday as he announced Noor had been charged with third-degree murder and second-degree manslaughter counts.

"There is no evidence Noor encountered a threat, appreciated a threat, investigated a threat or confirmed a threat that justified his decision to use deadly force," Mr Freeman told reporters.

"Instead, Officer Noor recklessly and intentionally fired his hand gun from the passenger seat in disregard for human life."

Mr Freeman described how Noor and his partner, Officer Matthew Harrity, responded to Ms Damond's 911 call about a potential sexual assault in an alley behind her Minneapolis home just before midnight on July 15 last year.

Ms Damond, 40, originally from Sydney, had heard what she though were a woman's screams.

Officer Harrity and Noor pulled up in the alley, did not see anything and Noor typed into their car computer "code four", meaning no assistance was needed, the prosecutor said.

Officer Harrity allegedly then heard a muffled voice or whisper, "a thump" behind him on the squad car and caught a glimpse of a person's head and shoulders outside the driver's side door.

"Importantly he could not see the person's hands and estimated the person was two feet away from him," Mr Freeman said.

"Harrity saw no weapons.

"However Harrity claimed he was startled, took his gun out of his holster and held it against his rib cage pointing downward.

"Harrity said from the driver's seat he had a better vantage point to determine a threat on his side of the car than Officer Noor did from the passenger side."